Method for Requesting Domain Transfer and Terminal and Server Thereof

1. A method for performing a domain transfer, the method comprising: determining, by a terminal, whether to perform a domain transfer of a session from a first domain to a second domain, wherein the determining is based on an operator policy and radio conditions, wherein the operator policy is received by the terminal from a network, wherein the operator policy includes first information indicating an operator's preferred domain and second information indicating a domain transfer level, wherein the domain transfer level indicates a first domain transfer level or a second domain transfer level, and wherein the first domain transfer level indicates that the domain transfer needs to be performed as indicated by the network, and the second domain transfer level indicates that the domain transfer is performed based on a decision of the terminal.

2. The method of claim 1 , wherein the domain transfer is performed based on the result of the determining.

3. The method of claim 1 , wherein the session is an ongoing session.

4. The method of claim 1 , wherein the session is related to a voice call.

5. The method of claim 1 , wherein the determining is further based on user preference information.

6. The method of claim 1 , wherein the first domain is a CS (Circuit Switched) domain, and the second domain is a PS (Packet Switched) domain.

7. The method of claim 6 , wherein the PS domain includes an IM (Internet protocol Multimedia) subsystem.

8. The method of claim 1 , wherein the first domain is a PS (Packet Switched) domain, and the second domain is a CS (Circuit Switched) domain.

9. The method of claim 8 , wherein the PS domain includes an IM (Internet protocol Multimedia) subsystem.

10. A terminal for performing a domain transfer, the terminal comprising: a processor configured to determine whether to perform a domain transfer of a session from a first domain to a second domain, wherein the determining is based on an operator policy and radio conditions, wherein the operator policy is received by the terminal from a network, wherein the operator policy includes first information indicating an operator's preferred domain and second information indicating a domain transfer level, wherein the domain transfer level indicates a first domain transfer level or a second domain transfer level, and wherein the first domain transfer level indicates that the domain transfer needs to be performed as indicated by the network, and the second domain transfer level indicates that the domain transfer is performed based on a decision of the terminal.